1. Field of the Invention
The invention relates generally to roller bearings, and more particularly to roller bearings for use in rotary or oscillatory applications, such as for supporting rotating or oscillating shafts.
2. Reference to Prior Art
Known roller bearings include various means for guiding and positioning rollers. For example, self-aligning angular contact roller bearings are shown in U.S. Pat. No. 2,387,962 issued Oct. 30, 1945 and U.S. Pat. No. 2,767,037 issued Oct. 16, 1956. In each of those patents the illustrated roller bearing includes an inner ring that provides a substantially spherical inner race surface, a pair of outer race surfaces having convex curvatures, and a pair of oppositely inclined rows of symmetrical hourglass-shaped rollers. Those roller bearings also include bearing cages or retainers to separate, guide and position the rollers in each row. An example of the above-described roller bearing is produced by Rexnord Corporation, Bearing Operation, Downers Grove, Ill. and has a Model No. DAS4-14A.
Japanese Patent No. 60-188617 illustrates a roller bearing having opposite rows of asymmetrical rollers and a center guide ring. The shape of the rollers and the center guide ring operate to guide and position the rollers in each row.
It is also known to provide integral collars or shoulders on the inner ring or the outer ring of a roller bearing to guide the rollers. An example of such a roller bearing is illustrated in U.S. Pat. No. 3,912,346 issued Oct. 14, 1975. In that roller bearing, an inner ring is provided with radially extending integral collars between which the rollers are confined.
The loads exerted on a bearing unit such as those described above are typically carried by the rollers in only one part of the unit at a time, that part being referred to as the "load zone". Especially where bearings are used in oscillatory applications, such as in aircraft flight control surfaces, it is desired that the rollers precess or index so that they are all cycled through the load zone. Cycling the rollers results in utilization of the entire race surface of each of the rollers to extend rolling contact fatigue life. Cycling the rollers also redistributes grease for improved lubrication of the bearing unit which in turn reduces fretting damage and improves the bearing unit's resistance to raceway corrosion. To cause such precessing or indexing of the rollers, it is known to use a retainer with skewed pockets. A known retainer has fingers or prongs inclined slightly to provide an inbalanced amount of skew to the rollers which causes the rollers to precess or index during oscillation of the bearing.
A disadvantage associated with the foregoing roller bearing units is the inclusion of a bearing cage, retainer, guide ring, integral collar, or the like. Such components are costly to produce and assemble as part of the bearing unit. Those components also occupy space within the bearing unit that could otherwise be used for additional rollers and/or additional lubricant.